I'm new here and fell in love with this forum. It's great to see I am not the only person who obsesses over this stuff. First, let me say that I have the Italian starters from sourdo.com. However, haven spoken with some artisan bread baker friends they think I could have easily saved the $20.

I have been working with sourdough for sometime in pizza, bread, pancakes, etc. and have mostly used my own homegrown starter to do so which may be why I am siding with their point. Their argument to me was that after my first few batches of dough the "Ischia" strain would have been completely replaced by the yeast strains locally present in the flour. This makes sense as with each feeding they are being divided and then outnumbered as competing yeast strains are introduced. Reinhart also makes this point in "The Bread Baker's Apprentice" though I feel that airborne yeast is not really a factor given the higher concentrations in the flour itself.

Given all of that. Couldn't you just start and feed your own italian culture using an imported Italian flour such as Caputo?

I have three cultures from sourdo.com (the 2 Italian and SF). My observations over the past four or five years is that if you keep them healthy they will retain their individual character. I typically feed mine with KAAP or KABF, but have used Caputo and other flours from time to time.

I don't think it is correct to say that the flora in the culture is "outnumbered as competing yeast strains are introduced" when feeding. I don't see how the math could possibly support that. I doubt it's even within several orders of magnitude. Also, the cells in the flour are dormant and weak. When I feed my culture, it doubles in a few hours. If I add some water to flour, it might take days to show any life.

I heard plenty of people say that local yeast will take over or that all cultures will become the same, but I've yet to hear a good explanation of how this would happen or see anyone demonstrate that it actually does.

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"We make great pizza, with sourdough when we can, commercial yeast when we must, but always great pizza."Craig's Neapolitan Garage

I say outnumbered because I typically use half of my culture before feeding, thereby cutting the culture's population in half and then adding competitors to their environment. Over time (say 10, 20, maybe 30 feedings) you can see how the strain can become diluted. If even a few of the competing yeast strains survive each feeding, the repeated feeding slowly works in that strains favor. For instance a 50lb bag of flour versus 100-200 gr of culture.

I feel the same way in that it doesn't quite make sense. In essence, it would mean their would be no such thing as San Francisco sourdough or any other popular strain.

Just to be safe I feed my Italian culture with Caputo flour only, and was thinking heck, I probably could have just started it from scratch.

From a previous thread on this topic, I offered, tongue firmly planted in cheek, to do the math to calculate the amount of time it would take a local strain to take over a starter if someone would like to supply the values for these variables:

At Time = 0, in 1 liter of starter there are:

x = number of starter organismsy = number of local invaderst = number of hours for starter population to doubleu = number of hours for invader population to doublez = my remaining life expectancy in hours

Although the environment is much more complicated than this, it is still intuitively obvious that the ratio of t/u would have to be extremely high for y>x in my lifetime. Assuming healthy starter and a very small y, we would likely be talking about a alien life form.

I say outnumbered because I typically use half of my culture before feeding, thereby cutting the culture's population in half and then adding competitors to their environment. Over time (say 10, 20, maybe 30 feedings) you can see how the strain can become diluted.

What you are forgetting is that by the time the yeast in the flour even wake up from dormancy, the yeast in the culture have probably already doubled, eaten the food, and pooped all over the place. It's not a good environment for a weakened strain to be introduced into.

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"We make great pizza, with sourdough when we can, commercial yeast when we must, but always great pizza."Craig's Neapolitan Garage

I used to believe that the yeast/bacteria present in the flour would eventually become the dominant life forms; it seemed intuitive. However, after reading a bit more on the topic, I no longer believe that. From what I've recently read in various places, is that given proper hygiene and a proper hospitable home, the established yeast will remain entirely dominant, for many of the reasons stated in the last post. They are already active and breading.

Cross contamination is probably a much bigger concern, when propagating multiple strains. Of course if you let your culture go dormant by not caring for it, then you're getting risky, but even then the risks seem very minimal at best given the ratios.

A previous poster mentioned airborne yeast, which is a common misconception. The yeast and bacteria are present in the flour, not in the air. Lots of nasties in the air, but nothing you're likely interested in propagating.

Cross contamination is probably a much bigger concern, when propagating multiple strains. Of course if you let your culture go dormant by not caring for it, then you're getting risky, but even then the risks seem very minimal at best given the ratios.

A previous poster mentioned airborne yeast, which is a common misconception. The yeast and bacteria are present in the flour, not in the air. Lots of nasties in the air, but nothing you're likely interested in propagating.

I keep my cultures in the fridge and feed them weekly outside of the fridge. I put them back in after I see a bit of activity. Do you think that is sufficient to avoid the cross contamination? Not sure that they ever fully go dormant. I occasionally will see a 1/2 tsp of hooch.

Also thanks for the input guys. I have to go defend my purchase to those bread bakers.

I keep my cultures in the fridge and feed them weekly outside of the fridge. I put them back in after I see a bit of activity. Do you think that is sufficient to avoid the cross contamination? Not sure that they ever fully go dormant. I occasionally will see a 1/2 tsp of hooch.

Also thanks for the input guys. I have to go defend my purchase to those bread bakers.

I don't think you will have any problems so long as you use clean utensils.

You probably don't need to feed them weekly in the fridge. I feed mine in the fridge every 3-4 months. Of course, they do go dormant. I keep one at room temp that I feed every 4 days or so.

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"We make great pizza, with sourdough when we can, commercial yeast when we must, but always great pizza."Craig's Neapolitan Garage

I usually feed with 40g/40g every week or so, just to keep things lively. But when we're making pizzas that takes care of itself. If I forget for a few weeks, it's not an issue. I feed so frequently, because it's rarely that we go more than two weeks without firing the oven.

What by cross contamination is what Craig said; Use clean tools. Never uses tools from mixing one strain to mix another.

A previous poster mentioned airborne yeast, which is a common misconception. The yeast and bacteria are present in the flour, not in the air. Lots of nasties in the air, but nothing you're likely interested in propagating.

On what exactly do you base this? My experience tends to prefer the "crapshoot" theory - there are microbes in the air, in the ingredients, on your hands, in your breath.... you never know what you're going to get.

Many years ago I was very much into capturing cultures and wanted to understand this topic better. I prepared 4 flour/water mixtures as identical as I could and placed two outdoors and the other two indoors. The two indoor samples showed just a little bit of activity after a week - not suitable for bread making. One of outdoor containers quickly developed a disgusting culture. After a few days, the other outdoor one produced a fairly nice culture that I used for many years until I discovered the vastly superior ones from sourdo.com.

Of course, this is more empirical that scientific, so I'm willing to be convinced that I'm wrong.

On what exactly do you base this? My experience tends to prefer the "crapshoot" theory - there are microbes in the air, in the ingredients, on your hands, in your breath.... you never know what you're going to get.

Many years ago I was very much into capturing cultures and wanted to understand this topic better. I prepared 4 flour/water mixtures as identical as I could and placed two outdoors and the other two indoors. The two indoor samples showed just a little bit of activity after a week - not suitable for bread making. One of outdoor containers quickly developed a disgusting culture. After a few days, the other outdoor one produced a fairly nice culture that I used for many years until I discovered the vastly superior ones from sourdo.com.

Of course, this is more empirical that scientific, so I'm willing to be convinced that I'm wrong.

Hi Bill,

I have issues with your experiment as the 2 outdoor cultures were subjected to a great deal of variables that most likely could not have been accounted for. Everything from sun and wind direction to animal waste would have effected your outcome. That being said I agree with you in that it's a "crapshoot" until someone scientifically proves otherwise. The problem here is that since we are dealing with living things, knowing for sure can be difficult.

What influences me towards the flour is that I am physically pouring the material into the vessel whereas there is a limited surface area on top which could be influenced by anything airborne. I also cover my culture so the exposure is limited to air inside of the container.

To give me some comfort that yeast would be able to eat the baked flour, I made two small test batches of 200%HR paste with 10% IDY. Both the baked and regular seem to show about the same level of activity. FYI - the flour is KABF.

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"We make great pizza, with sourdough when we can, commercial yeast when we must, but always great pizza."Craig's Neapolitan Garage

I sterilized* some flour and made two batches of 120% hydrated paste that have been left open in my kitchen. The baked flour made a noticeably thicker paste.

*The flour was held for 1 hour at 250F stirring every 15 minutes.

The heat has denatured proteins in the flour. Chains that were wrapped back on themselves have opened up, allowing them to form bonds with other chains and trapping more water molecules - hence the thicker paste. This might effect the establishment of a culture. The starches may be unaffected, but proteins such trace enzymes, amino acids, etc. that could affect microbial metabolism might be different between the two samples.

The heat has denatured proteins in the flour. Chains that were wrapped back on themselves have opened up, allowing them to form bonds with other chains and trapping more water molecules - hence the thicker paste. This might effect the establishment of a culture. The starches may be unaffected, but proteins such trace enzymes, amino acids, etc. that could affect microbial metabolism might be different between the two samples.

Yes, it will have that caveat. I couldn't think of another way with things I had on hand. I'm fresh out of ozone, and I loaned my electron gun to a friend. If someone just had to know the answer with certainty, UV might be the way to go.

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"We make great pizza, with sourdough when we can, commercial yeast when we must, but always great pizza."Craig's Neapolitan Garage

To give me some comfort that yeast would be able to eat the baked flour, I made two small test batches of 200%HR paste with 10% IDY. Both the baked and regular seem to show about the same level of activity. FYI - the flour is KABF.

This morning, both had activity, but the one with the regular flour had a lot more activity than the baked flour. Looks like there is some stuff that moved in by air. There was a pumpkin with a moldy spot within a couple feet of each and both got some nasty, smelly mold.

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"We make great pizza, with sourdough when we can, commercial yeast when we must, but always great pizza."Craig's Neapolitan Garage

There is no easy way to answer the subject question, but from my perspective the simple answer is no.

After using IDY for 3+ years with a cold ferment of 3-4 days, then recently switching to Ischia, no one in my local circle can taste the difference. For me, the key to good IDY is a healthy fermentation period. Healthy means that there is good activity in the dough when I pull it from the fridge (as measured by voids) and it smells neither yeasty nor alcohol-y.

Fortunately, I've never been accused of making the best pie on the forum, and as some know I'm partial to toppings, including bacon. But I'm still waiting to taste a starter-based pie that says viola! To be clear, some margherita pies taste better than others, but I've never been able to peel back a cornicione, sniff and say 'that's what I've been missing'.

I have a non-forum friend that took exception when we discussed the necessity of starter last week. Where we found common ground is that in baking bread, there is much hole structure to breathe in and enjoy than there is with pizza. He is really into making fresh bread, and I "get" that, because I would be too if it weren't so addictive.Dave

There is no easy way to answer the subject question, but from my perspective the simple answer is no.

This is, of course, true. It's not "necessary," per se. Notwithstanding, I can bake a much better pie with SD than with BY. Using a culture isn't for everyone either. That's not meant to be elitist or negative towards anyone. It is what it is. Using a natural culture is an additional level of complexity and difficulty and requires extra effort that some will find is not worth the potential gains.

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"We make great pizza, with sourdough when we can, commercial yeast when we must, but always great pizza."Craig's Neapolitan Garage